Western Tansymustard
Descurainia pinnata (Walt.) Britt.
Family: Brassicaceae, Mustard
Genus: Descurainia
Synonyms:
Other names: pinnate tansymustard
Nomenclature: pinnata = feathered (leaves)
Nativity / Invasiveness: Montana native plant, weed
Edible plant
Medicinal plant
Description

General: greenish to short-gray-hairy annual, with fine, star-shaped hairs and sometimes glandular above, 10-70 cm tall, from simple to usually freely branched.

Leaves: alternate, broadly lanceolate to oblanceolate, the lower ones stalked, 3-10 cm long, from bipinnate-pinnatifid to commonly pinnate-pinnatifid and somewhat toothed, the segments linear or broader. Upper leaves reduced, usually pinnatifid into linear segments.

Flowers: numerous in clusters, later greatly elongated. Flower stalks slender, 3-18 mm long, spreading and often somewhat S-shaped to ascending. The 4 sepals 1-2 mm long. The 4 petals pale to bright yellow, 1.5-3.5 mm long, oblanceolate, spreading, longer than the sepals. April-July.

Fruits: pods, 4-20 mm. long, about 1.5 mm broad, mostly with seeds in 2 rows at least near midlength and thus usually somewhat club-shaped or elliptic in outline, only inconspicuously, if at all constricted between seeds, narrowed and rounded abruptly to the barely perceptible style. Seeds 1-20 per cell, about 0.8 mm long.


Distribution

Plains, hills and disturbed areas, in most parts of MT. A very widespread, extremely variable, often weedy plant in most of the U.S. and s. Canada, except the far east.
Edible Uses

The young leaves of western tansymustard are edible cooked. However, they have a bitter flavor. If eaten as greens in the spring, they are said to have a salty flavor. The seedpods make an interesting mustard-flavored nibble. The seeds are edible raw or cooked. They have been used as a piņole. The seed has a mustard flavor and can be used to flavor soups or as a condiment with corn. The seed can also ground into a powder, mixed with cornmeal and used to make bread, or as a thickening for soups etc. In Mexico the seeds are made into a refreshing drink with lime juice, claret and syrup.



Medicinal Uses

The Navajo and Cahuilla Indians used this plant for medicinal purposes. The ground up seeds was used in the treatment of stomach complaints. A poultice of the plant has been used to ease the pain of toothache. An infusion of the leaves has been used as a wash on sores.



Sub taxa:

1 Plants glandular, especially among the flowers, often grayish-short-hairy. Pods 2-10 (12) mm long
    2 Pods more nearly oblong or club-shaped, 5-10 (12) mm long. Seeds often imperfectly in 2 rows. Petals from nearly white to dark yellow, often more than 1.5 (up to 3) mm long

      3 Plant greenish. Petals yellow, 2-3 mm long. On the e. base of the Rockies from Canada to TX, e. to N. England and Quebec.
      ssp. brachycarpa (Richards.) Detling
1 Plants non-glandular, or occasionally glandular above in var. filipes
    4 Pods 4-12 mm long, usually subequal to or longer than the stalks

      5 Petals about 1.5 mm long. Flower stalks mostly 4-6 mm long. From e. WA to NV, e. to MT and CO.
      ssp. nelsonii (Rydb.) Detling

      5 Petals 2-3 mm long. Flower stalks mostly 6-12 mm long. Rocky Mts. from e. B.C. to CO, grading into var. filipes.
      ssp. intermedia (Rydb.) Detling

    4 Pods 10-21 mm long, usually shorter than the stalks. From B.C. through e. WA to e. CA and NV, e. to MT and CO.
    ssp. filipes (Gray) Detling

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